The House passed the 21st Century Cures Act Friday with a resounding 344-77 vote, despite worries that a last-minute amendment might derail support.

The Cures Act, which reauthorizes the National Institutes of Health through 2018, is a bipartisan bill designed to promote breakthroughs in medical research with $2 billion in mandatory annual spending. An amendment introduced by Rep. Dave Brat, R-Va., threatened to throw the entire bill off track by providing discretionary funding for the new NIH and Cures Innovation Fund instead of mandatory funds. Despite worries among both parties, however, the Brat amendment was defeated, 141-281.

Brat, sticking to his guns, voted against final passage, telling reporters outside that he approved of the logic of the underlying bill but was opposed to setting up a mandatory program that adds to the existing "$127 trillion" entitlement burden.

Hoping for more votes for his amendment, Brat said, after the fact, "That’s the reason I put in the amendment, to show everyone this is the one issue we’re losing on. The kids are getting thrown under the bus on debt and entitlements.

"We’re supposed to be the party of fiscal discipline," he said. "So I wanna see messaging from our side that we’re serious on this."

Brat's fellow conservatives in the House Freedom Caucus also backed him, with no votes from at least 17 members, including committee chairmen Robert W. Goodlatte of Judiciary, Jeb Hensarling of Financial Services, K. Michael Conaway of Agriculture and Jeff Miller of Veterans' Affairs. Miller is also considering running for Republican Marco Rubio's Senate seat in Florida.

Brat's amendment also won some crossover votes from more moderate Republicans, including Reps. James B. Renacci of Ohio and Scott Rigell of Virginia. Rigell went on to vote for final passage, while Renacci opposed.

Another notable "yes" vote on the Brat amendment came from Rep. Paul D. Ryan, R-Wis., chairman of Ways and Means and a thought leader in the GOP who also has strong ties to leadership. The elected leadership slate of the House Republican Conference opposed the provision, excluding Vice Chairwoman Lynn Jenkins, R-Kan. However, Ryan and Jenkins both voted for the final bill.

A handful of Democrats voted against final passage, including Rep. Jackie Speier, D-Calif., an original co-sponsor. She opposed the eleventh-hour inclusion of language codifying existing prohibitions on federal funding for abortions, and joined in supporting fellow California Democrat Barbara Lee's amendment to strike the provision.

All but five Democrats voted in favor of Lee's amendment, but just seven of them — Lee and Speier included — felt compelled to vote against the underlying bill in the end.

"I am voting today to ... say 'no more' to the Republican contempt for women's, doctor's and scientist's right to make their own personal, professional or intellectual choices," said Jerrold Nadler, D-N.Y., one of those seven members.